Involvement of cell motility in tumor progression.

Since one crucial step in tumor progression consists of the acquisition of invasive and metastatic properties, it is important to analyze the mechanisms used by cancer cells to disperse. Among the possible mechanisms of cell dispersion, cell motility appears as a central phenomenon that still needs to be understood at the molecular level. Our experimental approach to the contribution of cell motility in carcinoma cell dissemination is based on the study of the NBT-II rat bladder carcinoma cell line. The epithelial cell line gives rise to isolated, actively migrating, fibroblast-like cells in response to specific stimuli (collagens and acidic fibroblast growth factor [aFGF]). Analysis of the scattering response indicates that the different stimuli can synergize, leading to increased motility and invasiveness. NBT-II cells have two types of response to aFGF: they can either proliferate or scatter. In addition, the two responses are mutually exclusive, suggesting that the cell status can dictate whether or not tumor cells will disperse after exposure to a scatter factor. Finally, recent studies on the involvement of epithelial-specific cadherins in the process of aFGF-induced cell scattering indicate that a sustained expression of E-cadherin is not sufficient to protect cells from dispersing. In conclusion, our experimental model offers the opportunity to dissect the molecular events leading to tumor cell dissemination.